The infusion bags relevant to this invention are those of the type which contain a measured quantity of substance enclosed in a membrane. Such bags are intended for infusion, for example in a hot liquid, and may incorporate a handle to facilitate both the suspension of the bag in the infusion liquid and the removal of the bag from the liquid. In some forms, the handle constitutes a short length of string stapled or glued to the bag. The free end of the string may have a tag attached for easy handling.
The bag itself may take any number of configurations. The most common form of bag represents a simple envelope or pouch, with walls of a thin porous paper-type material sealed on all edges (the "single chamber" bag). Another form of bag comprises a short length of tube or similar material. The free ends of the tube are fixed together so that the tube forms a loop which may be folded to any desired configuration (the "double chamber" or "flow-through" bag). In yet another form, the bag may be spherical or drop-shaped. It is to be understood that the present invention is applicable to all types of infusion bags, whatever their precise shape.
It is well recognised that infusion bags have gained immense popularity in recent years. In particular, infusion bags containing tea or herbs are in common use in many parts of the world and billions of such bags are sold every year.
While an infusion bag has many advantages and is generally convenient to use, it does suffer from two major drawbacks. The first arises after the bag has been immersed in the infusion liquid for the required period of time and it is desired to remove the bag from the liquid. It is invariably the case that residual liquid drips from the bag as it is withdrawn and care must be taken to ensure that the dripping liquid does not wet or stain surrounding surfaces or material.
The second drawback relates to the extraction of maximum flavour from the infusion bag. Simple infusion is not always sufficient for this purpose. Where the infusion bag is provided with a handle, the bag may be stirred through the infusion liquid by using the handle to oscillate (or "jiggle") the bag through the liquid and this can aid extraction. However, this method falls short of effecting maximum extraction.
Both drawbacks have been recognised and there have been attempts to overcome the drawbacks. For example, where the infusion bag is intended to be used to produce a cup of tea, some users employ a teaspoon or similar implement to squash the teabag between the teaspoon and the internal surface of the cup while this method can assist in extracting extra tea flavour from the bag, the method has very little success in preventing drips unless the bag can be held clear of the infusing liquid (hot water) during the operation. Normally, there is a maximum of two centimetres between the surface of the water in the cup and the lip of the cup. As a result, there is inadequate dry cup surface and the squashing method is not very effective. There is also the substantial danger that pressure on the inside surface of the cup, adjacent the lip, will cause the cup to tip and spill its contents.
In another prior art attempt to overcome the aforesaid drawbacks, a pair of tongs has been provided for squeezing infusion liquid and flavour from the bag. This method is somewhat more successful than the first method described above. However, one of the main advantages of infusion bags is their convenience in terms of storage and transportation, as well as their low manufacturing cost. It is not always convenient to have access to a pair of tongs for use with infusion bags; the provision of one of more pairs of tongs in cartons of infusion bags would add substantially to costs.
More sophisticated attempts to overcome these problems are disclosed in U.S. Pat. No. 2,878,927 (Haley), in U.S. Pat. No. 3,327,550 (Christopher) and in U.S. Pat. No. 3,396,032 (McCrae et al). However, each of these attempts involves a combination of an external harness on the infusion bag coupled with complicated means for tightening the harness and squeezing the bag.
It is an aim of the present invention to provide an improvement which overcomes or substantially alleviates the drawbacks referred to above and which moreover is inexpensive to implement.
Accordingly, this invention provides an improved infusion bag having a base and an apex and incorporating means for compressing the bag, characterised in that the compression means are provided in the form of a flexible handle at least a portion of which is located within the bag, the flexible handle being secured at or near the base and adapted to pass slidably through a substantial portion of the bag so that said handle is capable of compressing said bag by drawing said apex towards said base.
The invention also provides a method of manufacturing an improved infusion bag, comprising the steps of forming a bag and incorporating in the bag at least a portion of the compression means.
In a preferred embodiment of the infusion bag of the invention, the flexible handle is a string, forming a loop secured to the bag in at least one location in addition to the base. In use, the free end of the string (which may or may not have a tag attached) may be used to suspend the bag in the infusing liquid until it is desired to remove the bag from the liquid. At that time, as the bag is lifted clear of the infusing liquid by means of the string, the bag is compressed by sliding the bag along the string towards the base of the bag.
This compression action removes a substantial portion of infusing liquid from the bag and may also have the effect of maximising extraction of flavour from the bag. It is found that once the compressive force on the bag is released, provided the bag is still above the surface of the infusing liquid, there is insufficient infusing liquid remaining in the bag to cause dripping.
The compression means of the invention may be adapted to any configuration of infusion bag and may comprise systems other than that described above. Some of those other systems are described below.
The flexible handle, which may be a string or the like, may consist of a multi-stranded string, with different strands being attached to various parts of the bag. The purpose of this configuration may be to enhance compression of the bag, or to facilitate manufacture, or both.
In another form of the invention, the string may form a loop which is threaded through the bag or which is fixed to the bag in one or more locations.
In yet another form of the invention, two or more strings may be provided in order to enhance compression of the bag and/or to facilitate manufacture. The manner of fixing the string to the bag (or each string, if more than one) includes any method which is effective and convenient, including the use of knots, staples, glue, threading and the like. Depending on the effect desired, the method of fixing the string to the bag may permit the string to slide through the bag, or else the string may be anchored to the bag at one or more sites so that the string cannot slide through the bag at those sites. The choice of manner of fixing the string to the bag in any given configuration will be determined by the objectives in each situation and the range of choices will be readily apparent to one skilled in the art.
If desired, the improved infusion bag according to the invention may include means to facilitate compression of the bag. For example, where the handle is a short length of string it may be provided with a tag, button or similar device, slidably mounted on the string between the bag and the free end of the string, so that the device may be used to assist the compression by the user's fingers and to prevent scalding by contact with hot infusing liquid. In this embodiment, the tag may be releasably fixed to the free end of the string so that the bag resembles a conventional bag, with the tag carrying the usual manufacturer's trade mark, for example. However, when the bag is to be compressed, the tag is released from the end of the string and is able to slide towards the bag as already described. Where the string is multi-stranded or more than one string is provided, it is preferred that the means for facilitating compression of the bag, if used, are slidably mounted on all strands of the string or on all strings.
If desired, the bag may be manufactured so that the means for facilitating compression of the bag (such as a tag) are an integral part of the bag. For example, the tag may comprise a part of the bag as described in Australian Patent No. 118,215 (Sailsberg), with the zone where the tag joins the bag being weakened by perforations or the like, so that the tag, with string attached, may be detached from the remainder of the bag before infusion.
The invention is applicable to both single and double chambered infusion bags, inter alia. In the case of double-chambered bags, in which each chamber is attached to the other at the base and the apex, the string forming the compression means may be fastened at the base of the bag, so that the string passes between the two chambers through the apex. In this event, it may be desirable to fix the two chambers of the bag together (for example, by using glue or heat-sealing) at an additional point between the base and the apex so that during compression the two chambers do not fall away from the string, making compression less effective.
It will be noted that the compression means is regarded as within the infusion bag in accordance with the invention when the compression means passes between the two chambers.